Collaboration refers to the mutual engagement of two or more parties in the achievement of common goals. The focus is on the tools and functions that enable people to work together. Not just simply exchanging messages (i.e. communicating) but entering into a well-defined relationship to work together on the same task, e.g. collaboratively writing and editing a report.
Cooperation is similar to collaboration, in that it involves people working together but their relationship may be less well defined or there is a division of labour. For example, where each party completes their own tasks independently and the collection of all tasks achieves a final goal (e.g. tagging a document and adding it to a wiki) [cf. Mattessich/Monsey 1992, Roschelle/Teasley 1995, Miles 2009].